Genome Property Definition Page

Accession

GenProp0147

Name

glycine betaine biosynthesis from choline

Type

PATHWAY

Description

As a coping mechanism against osmotic stress, prokaryotic organisms accumulate osmolytes or osmoprotectants from exogenous sources, to counterbalance elevated osmolarities in the environment without affecting overall cell metabolism and structural integrity [1]. One of the most efficient osmoprotectants found in the environment is the compound glycine betaine [1]. Both gram positive and gram negative bacteria mediate osmotolerance either by direct uptake of glycine betaine from the environment, or by synthesis from exogenously supplied choline [2,3]. This property reflects the biosynthesis of the osmoprotectant glycine betaine from choline [4,5]. Biosynthesis of glycine betaine occurs via a two-step oxidative reaction requiring a terminal electron acceptor [2,3]. Choline dehydrogenase first catalyzes the conversion of exogenously supplied choline into the intermediate glycine betaine aldehyde, with subsequent oxidization by betaine aldehyde dehydrogenase into the osmoprotectant glycine betaine [2,3]. Both choline dehydrogenase and betaine aldehyde dehydrogenase are required for conversion of choline into glycine betaine [2,3].